A rolling closure for the roadway expansion joints of bridges is known from Swiss Patent Specification 581,752. The latter concerns a steel structure. A plurality of sliding bearers with cylindrical sliding faces being distributed over the width of the roadway are fastened on the first part of the roadway, the abutment. Flat swinging plates arranged next to one another are bolted onto the second part of the roadway, the bridge. Their free end rests by means of interchangeable sliding cams on two sliding bearers each. The swinging plates bridge the dilatation joint. Articulated at the free end of the swinging plates there is in each case a cylindrical sliding plate. The sliding plates likewise rest by means of sliding cams on the sliding faces of the sliding bearer. A tongue plate, fastened on the first part of the roadway and likewise segmented in the transverse direction of the roadway, overlaps the sliding plates. With this construction, if there is good alignment, a fairly smooth closure over the expansion joint can be achieved. However, this closure is expensive in production, and it requires a considerable construction depth, which leads to difficulties in particular in relatively thin parts of the bridge cantilevered transversely over the girder cross section. A major disadvantage of this crossing is the susceptibility to corrosion of the steel structure, in particular with regard to the use of thawing salt in winter. It is scarcely possible to provide a seal against salt solutions. These known closure must therefore be serviced and undergo expensive repairs at intervals of about 8 years.
In German Offenlegungsschrift 1,784,429, a sliding closure for an expansion joint is presented. In the case of these embodiments, the sliding plate consists of elastomeric material. As reinforcement, it has flexible bars which run in the longitudinal direction of the roadway, that is transversely to the expansion joint, and are bolted at the free end of the sliding plate to a guide plate and at the fastening end to a vertical steel plate arranged on the second part of the roadway. The sliding plate rests flatly on a row of steel bearers. In the case of some variants, these steel bearers bridge the expansion gap, are anchored on the first part of the roadway and protrude with their other end in a sliding manner into a box in the second part of the roadway. In still further embodiment, the steel bearers end at the free end of the first part of the roadway and, starting from there, have a cylindrical sliding face. These embodiments only have a modest load-bearing capacity. Due to the many steel parts exposed to corrosive salt water, the amount of servicing work is high.
In German Auslegeschrift 1,237,159, a roadway expansion joint crossing is described in which the two parts of the roadway engage one in the other in a tongue-like manner. The intermediate space between each tongue and the associated recess in what is respectively the other part of the roadway is covered in each case by a separate sliding closure. The closures consist of a series of interconnected metal strips which run transversely to the direction of travel and are guided in lateral guide rails. This construction too is expensive in production and in maintenance.
Finally, a closure in which the expansion joint is covered by a rubber plate is known from German Auslegeschrift 2,804,408. The rubber plate is bolted onto both parts of the roadway and has two grooves running parallel to the expansion joint both on its upper side and on its lower side. Flexurally rigid reinforcing plates are cast into the plate material. This crossing is only suitable for bridging relatively small expansion joints and generates very high restoring forces.